Surface-treated organic pigments

ABSTRACT

The present invention relates to surface-treated pigments of formula (I), wherein Ar 1  and Ar 2  are each independently of the other a phenyl or naphthalene group, n1 and n2 denote a value from 0 to 0.15, the sum of n1 and n2 being a value from 0.01 to 0.15, n is an integer 1 or 2, X 1  is a branched or unbranched alkyl radical or alkenyl radical having from 1 to 25 carbon atoms, it being possible for the alkyl radical to be interrupted by one or more S or O atoms, and is preferably a group —Y—(CH 2 ) m —R 1 , wherein Y is a group —CH 2 —, —O—, —S—, —C(O)O—, —C(O)—, —C(O)—NH—, —SO 2 NH— or —SO 2 — and R 1  is a hydrogen atom or a group —NR 2 R 3 , wherein R 2  and R 3  are each independently of the other a hydrogen atom or a C 1-6  alkyl radical, and m is an integer from 1 to 24, especially from 12 to 18, X 2  is a group —COOH, —SO 3 H or —P(O)OX 3 OX 4 , wherein X 3  and X 4  are each independently of the other a hydrogen atom or a C 1-6  alkyl radical, especially a hydrogen atom, and pigment denotes an organic pigment or a mixture of organic pigments, including solid solutions and crystalline solid solutions. Compared with untreated pigments, the surface-treated pigments exhibit better rheological properties and/or no warping in the pigmenting of partially crystalline plastics.

[0001] The present invention relates to surface-treated organicpigments, to a process for their preparation and to their use incolouring a high molecular weight organic material. Compared withuntreated pigments, the surface-treated pigments exhibit betterrheological properties and/or no warping in the pigmenting of partiallycrystalline plastics.

[0002] WO 00/52102 relates to a process for the preparation ofsurface-modified pigments, including the preparation in a liquid mediumof a premix that comprises a metal nitrite or an organic nitrite and adiazotisable radical containing a) at least one aromatic group (phenyland naphthyl) or at least one C₁₋₂₀alkyl radical or a mixture thereofand b) at least one ionic group (including salts of —COOH or —SO₃H,NR₃X), an ionisable group (including —NH₂, —NR₂, —COOH or —SO₃H), anon-ionic group (including alkyl and aryl radicals) or a mixturethereof, the addition of a pigment to the premix and the mixing of thepigment and the premix under the action of strong shearing forces toobtain a reaction product that comprises a surface-modified product.

[0003] The surface-modified pigment is readily dispersible in an aqueoussystem and has good colour hue and colour intensity. The diazotisableorganic radical is typically used in a “treatment concentration” of from0.01 to 5.0 micromol/m² of the pigment, based on the nitrogen surface ofthe pigment.

[0004] WO 97/48769 relates to surface-modified pigments, for examplephthalocyanines or quinacridones, that have no primary amine groups, andhave at least one bonded organic group, the organic group containing a)at least one aromatic group and b) at least one ionic group, especiallya sulfonic acid group, a phosphonic acid group, a carboxylic acid groupor a salt thereof, or an ionisable group or a mixture of an ionic groupand an ionisable group. There are also described aqueous compositionsand ink compositions that comprise the surface-modified pigment. Thesurface-modified pigment is distinguished from the untreated pigment bybetter dispersibility, greater stability and a higher absolute zetapotential. Inks that comprise surface-treated pigments yield verywater-resistant prints.

[0005] WO 97/47699 relates to a modified pigment comprising a colourpigment containing at least one bonded organic group, the organic grouphaving the formula Ar—R¹ or Ar¹R²R³, wherein Ar and Ar¹ denote anaromatic group, R¹ is an aromatic or aliphatic group containing ahydrophobic group and a hydrophilic group, R² is a hydrophilic group andR³ is an aromatic or aliphatic group containing a hydrophobic group, theorganic group being present in a “treatment concentration” of from about0.10 to about 5.0 micromol/m² of the colour pigment.

[0006] U.S. Pat. No. 5,955,232 describes a toner composition thatcomprises modified pigment particles containing bonded organic groups,and styrene-polymer-based resin particles. As organic group there may bementioned inter alia —Ar—(CH₂)—NH₂, —Ar—(CH₂)—NHCH₃, —Ar—(CH₂)—N(CH₃)₂,—Ar—(CH₂)₂—N(CH₃)₂, —Ar—(CH₂)₂—NH₂, —Ar—(CH₂)₂—N(CH₃)₂ and—Ar—(CH₂)₂—NHCH₃, wherein Ar is an aromatic group.

[0007] U.S. Pat. No. 6,054,238 describes a toner composition thatcomprises modified pigment particles containing bonded organic groups,and styrene-polymer-based resin particles. As organic group there may bementioned inter alia —Ar—(CH₂)—N(CH₃)₂, —Ar—(CH₂)₂—N(CH₃)₂,—Ar—(CH₂)₂—NH₂ and —Ar—(CH₂)₂—NHCH₃, wherein Ar is an aromatic group.

[0008] The object of the present invention is to provide surface-treatedpigments that, compared with untreated pigments, have better rheologicalproperties and/or exhibit no warping in the pigmenting of partiallycrystalline plastics, wherein the coloristic properties of the pigmentsshould not be appreciably influenced by the modification of the pigmentsurface.

[0009] The problem has surprisingly been solved by surface-treatedpigments of formula

[0010] wherein Ar¹ and Ar² are each independently of the other a phenylor naphthalene group,

[0011] n1 and n2 denote a value from 0 to 0.15, the sum of n1 and n2being a value from 0.01 to 0.15,

[0012] n is an integer 1 or 2, preferably 1,

[0013] X¹ is a branched or unbranched alkyl radical or alkenyl radicalhaving from 1 to 25 carbon atoms, it being possible for the alkylradical to be interrupted by one or more S or O atoms, and is preferablya group —Y—(CH₂)_(m)R¹, wherein

[0014] Y is a group —CH₂—, —O—, —S—, —C(O)O—, —C(O)—, —C(O)—NH—, —SO₂NH—or —SO₂— and

[0015] R¹ is a hydrogen atom or a group —NR²R³, wherein

[0016] R² and R³ are each independently of the other a hydrogen atom ora C₁₋₆alkyl radical, and

[0017] m is an integer from 1 to 24, especially from 12 to 18,

[0018] X² is a group —COOH, —SO₃H or —P(O)OX³OX⁴, wherein

[0019] X³ and X⁴ are each independently of the other a hydrogen atom ora C₁₋₆alkyl radical, especially a hydrogen atom, and

[0020] pigment denotes an organic pigment or a mixture of organicpigments, including solid solutions and crystalline solid solutions.

[0021] The present invention relates also to a process for thepreparation of the surface-treated pigments of formula I according tothe invention, comprising the reaction of a diazonium salt of formula

[0022] wherein n, X¹, X², Ar¹ and Ar² are as defined above, with anorganic pigment or a mixture of organic pigments, including solidsolutions and crystalline solid solutions, optionally in the presence ofa reducing agent, and to the use of the surface-treated pigment offormula I in the colouring of a high molecular weight organic material.

[0023] The surface-treated pigments have improved rheology propertiesand improved dispersion stability and also exhibit very good glossvalues and fastness to light and to migration. The surface treatment ofthe pigment results especially in a reduction in the viscosity of thepigment dispersion, which enables the dispersion, for example asolvent-based automotive finish, to be loaded with a greater amount ofpigment, and can enable partially crystalline plastics to bemass-pigmented without warping. The coloristic properties of thepigments are not adversely affected by the surface modification.

[0024] According to the invention, the expression “surface-treatedpigment” means that the surface of the pigment has been chemicallymodified, that is to say groups X¹—Ar¹— and/or (X²)_(n)—Ar²— have beenbonded covalently to the surface of the pigment.

[0025] The pigment can in principle be any desired organic pigment,provided its surface can be modified by the process according to theinvention. The pigment is usually a pigment of the 1-aminoanthraquinone,anthraquinone, anthrapyrimidine, azo, azomethine, quinacridone,quinacridonequinone, quinophthalone, diketopyrrolopyrrole, dioxazine,flavanthrone, indanthrone, indigo, isoindoline, isoindolinone,isoviolanthrone, perinone, perylene, phthalocyanine, pyranthrone orthioindigo series, to the surface of which a group X—Ar— can be bondedchemically by dediazotisation. It has been shown that pigmentscontaining unsubstituted phenyl groups are especially suitable.According to the invention, the term “pigment” is to be understood asincluding also mixtures of the above-mentioned pigments and alsomixtures of the above-mentioned pigments with other pigments, includingsolid solutions and crystalline solid solutions, the mixtures consistingcustomarily of from 2 to 5, preferably 2 or 3, components. Solidsolutions and crystalline solid solutions of quinacridones aredescribed, for example, in U.S. Pat. No. 3,160,510. Examples includePigment Red 202, 207, 209 and 206 and Pigment Orange 48 and 49. Solidsolutions and crystalline solid solutions ofdiketopyrrolo[3,4-c]pyrroles (DPP) are described, for example, in U.S.Pat. No. 4,783,540, U.S. Pat. No. 5,529,623, U.S. Pat. No. 5,708,188 andU.S. Pat. No. 6,036,766. Solid solutions and crystalline solid solutionsof DPP-type pigments and non-DDP-type pigments, for example quinacridoneor quinacridonequinone, are described in U.S. Pat. No. 4,810,304, U.S.Pat. No. 5,472,496, U.S. Pat. No. 4,810,304 and U.S. Pat. No. 5,821,373.An example is a mixed phase of Pigment Red 254 and Pigment Violet 254(Γ-modification). Monophase solid solutions that contain asymmetricpyrrolo[3,4-c]pyrroles as host are described in U.S. Pat. No. 5,756,746.Preference is given to solid solutions and crystalline solid solutionsof C.I. Pigment Red 264 or C.I. Pigment Red 255.

[0026] The pigment is preferably selected from

[0027] quinacridones of formula

[0028] wherein R¹¹ and R¹² are each independently of the other hydrogen,halogen, C₁₋₂₄alkyl, especially methyl, C₁₋₆alkoxy, especially methoxy,or phenyl, preference being given to quinacridones of formula XI inwhich at least one of the radicals R¹¹ and R¹² is hydrogen,

[0029] pyrrolo[3,4-c]pyrroles of formula

[0030] wherein at least one of the radicals X⁸ and X⁹, preferably bothradicals X⁸ and X⁹, is/are a group of formula

[0031] and the other radical can be a group of formula

[0032] wherein R¹⁴ and R¹⁵ are each independently of the other ahydrogen atom, a halogen atom, a C₁₋₂₄alkyl radical, a C₁₋₆alkoxyradical, a C₁₋₁₈alkylthio radical, a C₁₋₁₈alkylamino radical, a phenylgroup, a trifluoromethyl group or a group CN or NO₂, with the provisothat at least one of the radicals R¹⁴ and R¹⁵ is not a hydrogen atom,

[0033] T is —CH₂—, —CH(CH₃)—, —C(CH₃)₂—, —CH═N—, —N═N—, —O—, —S—, —SO—,—SO₂— or —NR¹⁸—, wherein R¹⁶ is hydrogen or C₁₋₆alkyl, especially methylor ethyl,

[0034] copper phthalocyanines of formula

[0035] which can be unsubstituted or substituted by from 1 to 5 chlorineatoms,

[0036] 1-aminoanthraquinone and anthraquinone pigments of formula

[0037] which X¹⁰ is a group

[0038] or dioxazines of formula

[0039] and indanthrones of formula

[0040] which can be unsubstituted or substituted by 1 or 2 chlorineatoms,

[0041] wherein X⁵ is a C₁₋₄alkoxy radical, especially ethoxy, X⁶ is abenzoylamino group and X⁷ is a chlorine atom or a radical NHC(O)CH₃;mixtures of the above-mentioned pigments, including solid solutions andcrystalline solid solutions, also being included.

[0042] The pigment is especially Pigment Blue 15:p, wherein p is aninteger from 1 to 6, C.I. Pigment Red 255, C.I. Pigment Red 264, C.I.Pigment Violet 19, C.I. Pigment Red 177, C.I. Pigment Blue 60 or a solidsolution of C.I. Pigment Red 264 or C.I. Pigment Red 255.

[0043] Examples of a (straight-chain or branched) C₁₋₂₄alkyl radical arelisted hereinafter in the explanation of the group X¹. Examples of a(straight-chain or branched) C₁₋₆alkoxy radical are methoxy, ethoxy,n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, amyloxy,isoamyloxy and tert-amyloxy. Examples of a (straight-chain or branched)C₁₋₁₈alkylthio radical are methylthio, ethylthio, n-propylthio,isopropylthio, n-butylthio, sec-butylthio, tert-butylthio, amylthio,isoamylthio and tert-amylthio, heptylthio, octylthio, isooctylthio,nonylthio, decylthio, undecylthio, dodecylthio, tetradecylthio,pentadecylthio, hexadecylthio, heptadecylthio and octadecylthio.Examples of a (straight-chain or branched) C₁₋₁₈alkylamino radical aremethylamino, ethylamino, n-propylamino, isopropylamino, n-butylamino,sec-butylamino, tert-butylamino, amylamino, isoamylamino andtert-amylamino, heptylamino, octylamino, isooctylamino, nonylamino,decylamino, undecylamino, dodecylamino, tetradecylamino,pentadecylamino, hexadecylamino, heptadecylamino and octadecylamino.According to the invention halogen atom is understood to mean afluorine, chlorine, bromine or iodine atom.

[0044] The meaning of the radicals Ar¹ and Ar² is determined by the easeof use and reactivity of the corresponding diazonium salt. The diazoniumsalt must, on the one hand, be sufficiently stable that it is easy touse and, on the other hand, must also be sufficiently reactive that byremoving nitrogen a covalent bond to the pigment is formed. It has notbeen possible to obtain satisfactory results with aliphatic diazoniumcompounds, whereas aromatic diazonium compounds, especially thosederived from phenyl and naphthalene, yield very good results.

[0045] The radicals X¹—Ar¹— and X²—Ar²— are preferably derived from1-aminonaphthalene substituted in the 5-position by X¹ and X²,respectively, and from 1-aminobenzene substituted in the 4-position byX¹ and X², respectively. Examples of amine compounds from which thediazonium compound and thus the group Ar¹—X¹— are derived, are procaine(H₂N-Ph-C(O)—O—(CH₂)₂—N(C₂H₅)₂), procainamide and4-hexadecylsulfonylaniline. Amine compounds from which the diazoniumcompound and thus the group Ar²—X²— are derived are especiallysulfanilic acid and 1-aminonaphthalene-5-sulfonic acid and4-aminophenylphosphonic acid as well as 1-amino- or2-aminonaphthalenedisulfonic acids, such as 4-aminonaphthalene-2,7, 2,6,1,6, 1,7, 1,5 or 1,3-disulfonic acids.

[0046] The sum of n1 and n2 is a value from 0.01 to 0.15, preferablyfrom 0.02 to 0.07, especially from 0.03 to 0.04, wherein n1 and n2indicate the number of groups X¹—Ar¹— and X²—Ar²— bonded to the surfaceof the pigment.

[0047] The group X¹ is a branched or unbranched C₁₋₂₅alkyl radical orC₂₋₂₅alkenyl radical, wherein the alkyl radical can be interrupted byone or more S or O atoms. Examples of a straight-chain or branchedC₁₋₂₅alkyl radical are methyl, ethyl, n-propyl, isopropyl, n-butyl,sec-butyl, tert-butyl, amyl, isoamyl and tert-amyl, heptyl, octyl,isooctyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, pentadecyl,hexadecyl, heptadecyl and octadecyl. Examples of a C₂-C₂₅alkenyl radicalare allyl, methallyl, isopropenyl, 2-butenyl, 3-butenyl, isobutenyl,n-penta-2,4-dienyl, 3-methyl-but-2-enyl, n-oct-2-enyl, n-dodec-2-enyl,isododecenyl, n-dodec-2-enyl and n-octadec-4-enyl. C₂₋₂₅Alkyl that isinterrupted one or more times by —O— or —S— is, for example, interruptedfrom 1 to 5 times, e.g. from 1 to 3 times or 1 or 2 times, bynon-consecutive-O-radicals or —S— radicals, respectively. The resultingstructural units are accordingly, for example: -A(CH₂)₂ACH₃,-A(CH₂CH₂A)₂CH₂CH₃, —CH₂-A-CH₃, —CH₂CH₂-A-CH₂CH₃, —[CH₂CH₂A]_(y)CH₃,wherein y=1-12, —(CH₂CH₂A)₅CH₂CH₃, —CH₂—CH(CH₃)-A-CH₂—CH₂CH₃ or—CH₂—CH(CH₃)-A-CH₂—CH₃, wherein A is —O— or —S—.

[0048] The group X¹ is preferably a group —Y—(CH₂)_(m)—R¹, wherein Y isa group —CH₂—, —O—, —S—, —C(O)O—, —C(O)—, —C(O)—NH—, —SO₂NH— or —SO₂—and R¹ is a hydrogen atom or a group —NR²R³, wherein R² and R³ are eachindependently of the other a hydrogen atom or a C₁₋₆-alkyl radical and mis an integer from 1 to 24. Compounds in which m is greater than 4,especially from 12 to 18, are especially suitable for mass-colouringpartially crystalline plastics.

[0049] The group X² is a group —COOH, —SO₃H or —P(O)OX³OX⁴, wherein X³and X⁴ are each independently of the other a hydrogen atom or aC₁₋₆alkyl radical, especially a hydrogen atom.

[0050] In the surface-treated pigments of formula I, the following arepossible: n1>0 and n2=0, n1=0 and n2>0 and n1>0 and n2>0, which resultin surface-treated pigments of formulae

[0051] wherein n, pigment, X¹, X², Ar¹ and Ar² are as defined above andn1 and n2 denote a value from 0.01 to 0.15, preferably from 0.02 to0.07, especially from 0.03 to 0.04.

[0052] The surface-treated pigments of formulae Ia, Ib and Ic haveimproved rheology properties and dispersion stability, thesurface-treated pigments of formula la in particular being suitable forthe warp-free mass-pigmenting of partially crystalline plastics.Compared with surface-treated pigments of formulae Ia and Ib, it ispossible to obtain improved rheological properties in thesurface-treated pigments of formula Ic by the simultaneous presence ofnon-ionic, especially basic, groups and acid groups on the pigmentsurface.

[0053] The present invention relates also to a process for thepreparation of the surface-treated pigments of formula I according tothe invention. The process comprises the reaction of a diazonium salt offormula

[0054] wherein n, X¹, X², Ar¹ and Ar² are as defined above, with apigment or a mixture of pigments, including solid solutions andcrystalline solid solutions, optionally in the presence of a reducingagent.

[0055] Depending on the stability and reactivity of the diazonium salt,the dediazotisation can be carried out advantageously in the presence ofa reducing agent selected from copper(I) and copper(II) compounds, forexample Cu₂O or CuSO₄, iron(II) compounds, for example Fe₂SO₄, tin(II)compounds, for example SnCl₂, hydroquinones (according to the inventionhydroquinones are to be understood as including all compounds based onthe 1,4-benzene-diol system of the hydroquinone, for examplehydroquinone or ubiquinones), and sodium iodide, Fe₂SO₄ being preferredas reducing agent. As a result of using the reducing agents, thereaction time can be lowered from hours to minutes and in some cases theyields can be radically increased (see F. W. Wassmundt et al., J. Org.Chem. 1995, 60, 1713-1719 and 4991-4994).

[0056] Normally the pigment to be treated, for example in the form of apress cake, is introduced in a solvent. The diazonium salt isadvantageously prepared separately by reacting a metal nitrite or anorganic nitrite with the aromatic amine compound X¹—Ar¹—NH₂ and/orX²—Ar²—NH₂ and is subsequently added to the pigment to be treated.Alternatively, the diazonium salt can also be prepared in situ, eitherby introducing the aromatic amine compound or the metal nitrite or theorganic nitrite together with the pigment and adding the secondcomponent, or by introducing the pigment and adding the metal nitrite orthe organic nitrite and the aromatic amine compound separately. Thereducing agent, when it is used, is advantageously introduced togetherwith the pigment.

[0057] Preferred solvents are water, water-containing solvents andprotic solvents, such as alcohols, alcohol-containing solvents andmixtures thereof. Water is especially preferred. Metal nitrites andorganic nitrites that can be used in the process according to theinvention include, for example, ammonium nitrite, butyl nitrite,dicyclohexylammonium nitrite, ethyl nitrite, isoamyl nitrite, lithiumnitrite, sodium nitrite, potassium nitrite and zinc nitrite. Thereaction temperature and the reaction time are generally from 0° C. to90° C. and from 15 minutes to 12 hours, both the reaction temperatureand the reaction time depending to a great extent upon the reactionconditions selected. Depending on the nitrite selected, an acid orneutral pH is established.

[0058] In general, the pigment is dispersed in water, optionally withthe addition of customary auxiliaries, such as dispersion auxiliaries,for example polar polymers, such as polyvinyl alcohol or copolymers ofvinylpyrrolidone and vinyl acetate. The diazonium salt is preparedseparately by reacting the primary amine with sodium nitrite and conc.hydrochloric acid in water at from 0 to 5° C. The diazonium saltprepared separately is added at low temperature (0 to 4° C.). Dependingon the diazonium salt, the temperature is slowly increased to from 20 to70° C. and the pH is increased up to 5 by the addition of a base, suchas sodium hydroxide, sodium phosphate, sodium carbonate, ammonia etc.The reducing agent, when it is used, can be added before or after theaddition of the diazonium salt. Depending on the surface-treatedpigment, the pigment is isolated by filtration at the pH prevailing atthe end of the reaction or at a higher pH, and washed and dried incustomary manner. The excess reducing agent or the oxidised reducingagent is separated off by customary processes.

[0059] Surface-treated pigments of formula I can be used, for example,in the mass-colouring of high molecular weight organic materials. Theyare suitable especially for pigmenting plastics, surface coatings andprinting inks.

[0060] The high molecular weight organic material to be colouredaccording to the invention may be of natural or synthetic origin andusually has a molecular weight in the range of from 10³ to 10⁸ g/mol. Itcan be, for example, a natural resin or a drying oil, rubber or caseinor a modified natural substance, such as chlorinated rubber, anoil-modified alkyd resin, viscose, a cellulose ether or ester, such ascellulose acetate, cellulose propionate, cellulose aceto-butyrate ornitrocellulose, but is especially a completely synthetic organic polymer(a thermosetting plastic or a thermoplastic), as are obtained bypolymerisation, polycondensation or polyaddition, for examplepolyolefins, such as polyethylene, polypropylene or polyisobutylene,substituted polyolefins, such as polymerisation products of vinylchloride, vinyl acetate, styrene, acrylonitrile, acrylic acid esterand/or methacrylic acid ester or butadiene, and also copolymerisationproducts of the said monomers, especially ABS or EVA.

[0061] From the range of polyaddition resins and polycondensation resinsthere may be mentioned condensation products of formaldehyde withphenols, so-called phenoplasts, and condensation products offormaldehyde with urea, thiourea and melamine, so-called aminoplasts,polyesters used as surface-coating resins, either saturated, such asalkyd resins, or unsaturated, such as maleic resins, and also linearpolyesters and polyamides or silicones.

[0062] The mentioned high molecular weight compounds may be presentindividually or in mixtures as plastic masses or melts that can, ifdesired, be spun into fibres.

[0063] They can also be in the form of their monomers or in thepolymerised state in dissolved form as film formers or binders forsurface coatings or for printing inks, such as boiled linseed oil,nitrocellulose, alkyd resins, melamine resins, urea-formaldehyde resinsor acrylic resins.

[0064] The pigmenting of the high molecular weight organic substancesusing the surface-treated pigments of formula I according to theinvention is effected, for example, by admixing a surface-treatedpigment of formula I, optionally in the form of a masterbatch, with suchsubstrates using roll mills or mixing or grinding apparatuses. Thepigmented material is then generally brought into its desired final formby processes known per se, such as calendering, compression moulding,extrusion, spread-coating, casting or injection-moulding. In order toobtain different colour shades, it is also possible to add to the highmolecular weight organic substances fillers or other colour-impartingconstituents, such as white, coloured or black pigments orspecial-effect pigments, in each case in the desired amount.

[0065] For the pigmenting of surface coatings, the high molecular weightorganic materials and the surface-treated pigments according to theinvention are finely dispersed or dissolved, optionally together withadditives, such as fillers, other pigments, siccatives or plasticisers,generally in an organic and/or aqueous solvent or solvent mixture. It isalso possible to use a procedure in which the individual components aredispersed or dissolved separately or in which a plurality thereof aredispersed or dissolved together, and only then are all of the componentscombined.

[0066] A further embodiment accordingly relates also to mass-colouredhigh molecular weight organic material containing

[0067] (a) from 0.05 to 70% by weight, based on the sum of (a) and (b),of the surface-treated pigment of formula I according to the invention,and

[0068] (b) from 99.95 to 30% by weight, based on the sum of (a) and (b),of a high molecular weight organic material.

[0069] The material can be a ready-to-use composition or an articleformed therefrom, or a masterbatch, for example in the form of granules.Where appropriate, the high molecular weight organic material colouredaccording to the invention can also comprise customary additives, forexample stabilisers or further inorganic, metallic or organic pigments,such as rutile, carbon black, aluminium flakes, mica, which may or maynot be coated, or any desired coloured pigments.

[0070] The mass-colouring of the high molecular weight organic materialusing the surface-treated pigment of formula I is carried out, forexample, by mixing and processing the high molecular weight organicmaterial with the surface-treated pigment of formula I according to theinvention, optionally in the form of a masterbatch, in a manner knownper se.

[0071] The surface-treated pigments of formula I are preferably used insurface coatings, especially in solvent-based automotive finishes, wherethey make a higher pigment content possible. Surface-treated pigments offormula Ia, preferably those in which m is an integer from 4 to 20,especially from 12 to 18, can be used especially in the pigmenting ofpartially crystalline plastics, especially those processed byinjection-moulding, without the occurrence of warping. In the plasticsprocessing industry “warping” is a known major problem observed inpartially crystalline plastics following injection-moulding, moreespecially in the presence of organic pigments.

[0072] “Partially crystalline plastics” are to be understood as meaningthose plastics that on solidification form small crystalline nuclei oraggregates (for example spherulites or quadrites), including plasticsthat exhibit such behaviour only in the presence of nucleating agents(for example organic pigments).

[0073] Partially crystalline plastics are generally thermoplastic highmolecular weight organic materials having a molecular weight (M_(w)) offrom 10⁴ to 10⁸, especially from 10⁵ to 10⁷, and a degree ofcrystallinity (X_(c)) of from 10 to 99.9%, preferably from 40 to 99%,especially from 80% to 99%. Preferred partially crystalline plastics arehomopolymers, block or random copolymers and terpolymers of ethylene,propylene, butylene, styrene and/or divinylbenzene, especiallyα-olefins, such as HDPE, LDPE, polypropylene and polystyrene, and alsopolyesters, such as PET, polyamides, such as nylon 6 and nylon 66, andthermoplastic ionomers.

[0074] Especially preferred partially crystalline plastics arepolyolefins, especially polyethylene of high density and polypropylene.

[0075] The partially crystalline plastics may optionally also comprisecustomary amounts of additives, for example, stabilisers, opticalbrighteners, fillers and/or lubricants.

[0076] The invention accordingly relates also to a compositioncomprising a partially crystalline plastics and a surface-treatedpigment of formula I.

[0077] The preparation is carried out according to customary processes,for example by mixing the surface-treated pigments of formula I with theplastics granules or powder, and extruding the mixture to form fibres,films or granules. The latter can then be formed into articles, forexample by injection-moulding, such articles exhibiting scarcely anywarping on solidification or in many cases no warping at all.

[0078] Where appropriate, of course, additives may also be used incustomary manner as further additional ingredients.

[0079] The surface-treated pigments according to the invention exhibitimproved rheology properties and improved dispersion stability and canenable partially crystalline plastics to be mass-pigmented withoutwarping. The surface treatment of the pigment results especially in areduction in the viscosity of the pigment dispersion, which enables thedispersion to be loaded with a greater amount of pigment. The coloristicproperties of the pigments are not adversely affected by the surfacemodification. The surface-treated pigments are distinguished especiallyby very good gloss values and fastness to light and to migration.

[0080] The following Examples illustrate the invention without limitingthe scope thereof.

EXAMPLE 1 Reaction of C.I. Pigment Red 255 with the Diazonium Salt ofProcaine (H₂N-Ph-C(O)—O—(CH₂)₂—N(C₂H₅)₂)

[0081] 21.8 g of a 43.8% aqueous press cake of C.I. Pigment Red 255 aredispersed in 125 ml of water, together with 2.8 g of iron(II) sulfate(FeSO₄.7H₂O) for 16 hours. 2.73 g of procaine.HCl (FLUKA) in 7.5 g ofwater and 3.5 ml of conc. hydrochloric acid are treated separately with2.6 ml of 4M NaNO₂ solution at from 0 to 4° C. The diazonium salt isslowly added to the pigment suspension. The suspension is stirred atroom temperature for 1.5 hours. The pH of the suspension is increased to9.5-10 with 2N NaOH solution. The suspension is filtered and the residueis washed neutral with water. The filtration residue is dried at 80° C.and then pulverised.

EXAMPLE 2 Reaction of C.I. Pigment Red 255 with the Diazonium Salt ofProcainamide (H₂-Ph-C(O)—NH—(CH₂)₂—N(C₂H₅)₂)

[0082] Example 1 is repeated, except that 2.72 g of procainamide.HCl areused instead of 2.73 g of procaine.HCl.

EXAMPLE 3 Reaction of C.I. Pigment Red 264 with the Diazonium Salt ofProcainamide (HeN-Ph-C(O)—NH—(CH₂)₂—N(C₂H₅)₂)

[0083] Example 2 is repeated, except that instead of C.I. Pigment Red255 the corresponding amount of C.I. Pigment Red 264 is used.

EXAMPLE 4 Reaction of C.I. Pigment Blue 15:3 with the Diazonium Salt of4-hexadecyl-sulfonylaniline

[0084] 5 g of C.I. Pigment Blue 15:3 are dispersed in 50 ml of water and1 ml of isopropanol. 0.5 g of 4-hexadecylsulfonylaniline in 8 g of waterand 0.9 ml of conc. hydrochloric acid are treated separately with 0.4 mlof 4M NaNO₂ solution at from 0 to 4° C. The diazonium salt is slowlyadded to the pigment suspension. The suspension is stirred at roomtemperature for 2 hours, slowly heated to 65° C., stirred for one hourat 50° C. and filtered, and the residue is washed neutral with water.The filtration residue is dried at 80° C. and then pulverised.

EXAMPLE 5

[0085] 2.0 g of each of the products obtained according to Examples 1 to3 are dispersed for three hours according to a customary method in thefollowing polyester surface-coating system:

[0086] 5.5 g of ®Dynapol H700 (Dynamit Nobel)

[0087] 0.6 g of ®Solsperse 24000 (Avecia)

[0088] 4.8 g of xylene

[0089] 7.1 g of butyl acetate

[0090] The dispersions are made up into a lake with 2.2 g of ®MaprenalMF 650 (Hoechst) and 4.5 g of a 20% solution of cellulose acetobutyratein butanol/xylene 2:1 (®CAB 531.1, Eastman Chem.). The application ofthe resulting colour lake is effected by discharging it onto a glassplate. Prior to baking in a circulating-air drying cabinet (30′ at 120°C.), the plate is exposed to air for 20 minutes at an inclination of90°. The gloss values, measured using a gloss meter (™ZGM 1020,Zehntner) at an inclination of 20° in accordance with DIN 67530, arehigher than those of untreated pigments.

EXAMPLE 6

[0091] 1.4 g of the pigment obtained in Example 4 and 700 g of Stamilan®9089U (HDPE/DSM) are mixed dry in a tumbler mixer for 10 minutes. Themixture is extruded in a single-screw extruder at 200° C. The resultinggranules are processed in an injection-moulding machine at 240° C. toform plates of the dimensions 174×49×2.5 mm. After injection-moulding,the plates are conditioned at a temperature of 90° C. in a water bathfor 30 minutes and stored at room temperature (˜23° C.) for at least 15hours. The plates are then measured precisely.

[0092] The results are comparable to those obtained using colourlessStamilan® 9089U. In contrast to plates with untreated pigments alone,the plates obtained are virtually completely warp-free.

EXAMPLE 7

[0093] To determine the flow behaviour, the viscosity of dispersionscomprising the products of Examples 1, 2 or 3 is determined using a®Rotovisco RV20 viscometer (HAAKE, measuring temperature 25° C.,measuring system SV-SP, shearing range 0-500 s⁻¹). Compared withuntreated pigments, the lake dispersions obtained with the productsaccording to Examples 1 to 3 exhibit markedly better flow behaviour.

EXAMPLE 8 Reaction of C.I. Pigment Red 264 with the Diazonium Salt ofnaphthylamine-5-sulfonic Acid

[0094] 72.8 g of a 41.2% aqueous press cake of C.I. Pigment Red 264 aredispersed in 550 ml of water for 16 hours. 1.67 g ofnaphthylamine-5-sulfonic acid in 8 g of water and 2.7 ml of conc.hydrochloric acid are treated separately with 2.1 ml of 4M NaNO₂solution at from 0 to 4° C. The diazonium salt is slowly added to thepigment suspension. The suspension is stirred at room temperature for 2hours, heated slowly to 50° C., stirred for one hour at 50° C. andfiltered, and the residue is washed neutral with water. The filtrationresidue is dried at 80° C. and then pulverised.

EXAMPLE 9

[0095] Example 8 is repeated, the diazonium salt being prepared in situ.

EXAMPLE 10 Reaction of C.I. Pigment Red 255 with the Diazonium Salt ofnaphthylamine-5-sulfonic Acid

[0096] Example 8 is repeated, except that instead of C.I. Pigment Red264 the corresponding amount of C.I. Pigment Red 255 is used.

EXAMPLE 11 Reaction of C.I. Pigment Violet 19 with the Diazonium Salt ofnaphthylamine-5-sulfonic Acid

[0097] Example 8 is repeated, except that instead of C.I. Pigment Red264 the corresponding amount of the quinacridone pigment C.I. PigmentViolet 19 is used.

EXAMPLE 12 Reaction of C.I. Pigment Red 255 with the Diazonium Salt ofSulfanilic Acid

[0098] 21.8 g of a 46% aqueous press cake of C.I. Pigment Red 255 aredispersed in 100 ml of water together with 1.2 g of iron(II) sulfate(FeSO₄.7H₂O) for 4 hours. 0.7 g of sulfanilic acid in 2.9 g of water and1.38 g of conc. hydrochloric acid are treated separately with 1.08 ml of4M NaNO₂ solution at 4° C. The diazonium salt is slowly added to thepigment suspension. The suspension is then stirred at room temperaturefor a further 2 hours and filtered, and the residue is washed neutralwith water. The filtration residue is dried at 80° C. and thenpulverised.

EXAMPLE 13

[0099] Example 12 is repeated, the diazonium salt being prepared insitu.

EXAMPLE 14 Reaction of C.I. Pigment Red 264 with the Diazonium Salt ofSulfanilic Acid

[0100] 45.6 g of a 43.8% aqueous press cake of C.I. Pigment Red 264 aredispersed in 200 ml of water together with 5.6 g of iron(II) sulfate(FeSO₄.7H₂O) for 16 hours. 3.5 g of sulfanilic acid in 15 g of water and7 ml of conc. hydrochloric acid are treated separately with 5.5 ml of 4MNaNO₂ solution at from 0 to 4° C. The diazonium salt is slowly added tothe pigment suspension. The suspension is stirred at room temperaturefor 2 hours and filtered, and the residue is washed neutral with water.The filtration residue is dried at 80° C. and then pulverised.

EXAMPLE 15 Reaction of C.I. Pigment Red 255 with the Diazonium Salt of4-amino-phenylphosphonate

[0101] 21.8 g of a 46% aqueous press cake of C.I. Pigment Red 255 aredispersed in 100 ml of water together with 1.2 g of iron(II) sulfate(FeSO₄.7H₂O) for 4 hours.

[0102] 0.7 g of 4-aminophenylphosphonic acid (FLUKA) in 2.9 g of waterand 1.38 g of conc. hydrochloric acid are treated separately with 1.08ml of 4M NaNO₂ solution at 4° C. The diazonium salt is slowly added tothe pigment suspension. The suspension is stirred at room temperaturefor 1 hour and filtered, and the residue is washed neutral with water.The filtration residue is dried at 80° C. and then pulverised.

EXAMPLE 16

[0103] 2.0 g of each of the products obtained according to Examples 8 to15 are dispersed for three hours according to a customary method in thefollowing polyester surface-coating system:

[0104] 5.5 g of ®Dynapol H700 (Dynamit Nobel)

[0105] 0.6 9 of ®Solsperse 24000 (Avecia)

[0106] 4.8 g of xylene

[0107] 7.1 g of butyl acetate

[0108] The dispersions are made up into a lake with 2.2 g of ®MaprenalMF 650 (Hoechst) and 4.5 g of a 20% solution of cellulose acetobutyratein butanollxylene 2:1 (®CAB 531.1, Eastman Chem.). The application ofthe resulting colour lake is effected by discharging it onto a glassplate. Prior to baking in a circulating-air drying cabinet (30′ at 120°C.), the plate is exposed to air for 20 minutes at an inclination of90°. The gloss values, measured using a gloss meter (™ZGM 1020,Zehntner) at an inclination of 200 in accordance with DIN 67530, arehigher than those of untreated pigments.

EXAMPLE 17

[0109] To determine flow behaviour, the viscosity of dispersionscomprising the products of Examples 8 to 15 is determined using a®Rotovisco RV20 viscometer (HAAKE, measuring temperature 25° C.,measuring system SV-SP, shearing range 0-500 s⁻¹).

[0110] Compared with untreated pigments, the lake dispersions obtainedwith the products according to Examples 1 to 3 exhibit markedly improvedflow behaviour.

What is claimed is:
 1. A surface-treated pigment of formula

wherein Ar¹ and Ar² are each independently of the other a phenyl ornaphthalene group, n is an integer 1 or 2, n1 and n2 denote a value from0 to 0.15, the sum of n1 and n2 being a value from 0.01 to 0.15, X¹ is abranched or unbranched alkyl radical or alkenyl radical having from 1 to25 carbon atoms, it being possible for the alkyl radical to beinterrupted by one or more S or O atoms, and is preferably a group—Y—(CH₂)_(m)—R¹, wherein Y is a group —CH₂—, —O—, —S—, —C(O)O—, —C(O)—,—C(O)—NH—, —SO₂NH— or —SO₂ and R¹ is a hydrogen atom or a group —NR²R³,wherein R² and R³ are each independently of the other a hydrogen atom ora C₁₋₆alkyl radical, and m is an integer from 1 to 24, especially from12 to 18, X² is a group —COOH, —SO₃H or —P(O)OX³OX⁴, wherein X³ and X⁴are each independently of the other a hydrogen atom or a C₁₋₆alkylradical, especially a hydrogen atom, and pigment denotes an organicpigment or a mixture of organic pigments, including a solid solution ora crystalline solid solution.
 2. A surface-treated pigment according toclaim 1, wherein the surface-treated pigment has the following formula

wherein n, pigment, X¹, X², Ar¹ and Ar² are as defined in claim 1 and n1and n2 denote a value from 0.01 to 0.15, preferably from 0.02 to 0.07,especially from 0.03 to 0.04.
 3. A surface-treated pigment according toeither claim 1 or claim 2, wherein the organic pigment is a pigment ofthe 1-aminoanthraquinone, anthraquinone, anthrapyrimidine, azo,azomethine, quinacridone, quinacridonequinone, quinophthalone,diketopyrrolopyrrole, dioxazine, flavanthrone, indanthrone, indigo,isoindoline, isoindolinone, isoviolanthrone, pennone, perylene,phthalocyanine, pyranthrone or thioindigo series, a mixture of suchpigments, including a solid solution or a crystalline solid solution,also being included.
 4. A surface-treated pigment according to claim 3,wherein the pigment is selected from quinacridones of formula

wherein R¹¹ and R¹² are each independently of the other hydrogen,halogen, C₁₋₂₄alkyl, especially methyl, C₁₋₆alkoxy, especially methoxy,or phenyl, pyrrolo[3,4-c]pyrroles of formula

wherein at least one of the radicals X⁸ and X⁹ is a group of formula

and the other radical can be a group of formula

wherein R¹⁴ and R¹⁵ are each independently of the other a hydrogen atom,a halogen atom, a C₁₋₂₄alkyl radical, a C₁₋₆alkoxy radical, aC₁₋₁₈alkylthio radical, a C₁₋₁₈alkylamino radical, a phenyl group, atrifluoromethyl group or a group CN or NO₂, with the proviso that atleast one of the radicals R¹⁴ and R¹⁵ is not a hydrogen atom, T is—CH₂—, —CH(CH₃)—, —C(CH₃)₂—, —CH═N—, —N═N—, —O—, —S—, —SO—, —SO₂— or—NR¹⁶—, wherein R¹⁶ is hydrogen or C₁₋₆alkyl, especially methyl orethyl, and copper phthalocyanines of formula

which can be unsubstituted or substituted by from 1 to 5 chlorine atoms,1-aminoanthraquinone and anthraquinone pigments of formula

wherein X¹⁰ is a group

dioxazines of formula

and indanthrones of formula

which can be unsubstituted or substituted by 1 or 2 chlorine atoms,wherein X¹ is a C₁₋₄alkoxy radical, especially ethoxy, X⁶ is abenzoylamino group and X⁷ is a chlorine atom or a radical NHC(O)CH₃; amixture of such pigments, including a solid solution or a crystallinesolid solution, also being included.
 5. A surface-treated pigmentaccording to claim 4, wherein the pigment is derived from Pigment Blue15:p wherein p is an integer from 1 to 6, C.I. Pigment Red 255, C.I.Pigment Red 264, C.I. Pigment Violet 19, C.I. Pigment Red 177, C.I.Pigment Blue 60 or a solid solution of C.I. Pigment Red 264 or C.I.Pigment Red
 255. 6. A surface-treated pigment according to any one ofclaims 1 to 5, wherein Y is a group —CH₂—, —O—, —S—, —C(O)O—, —C(O)—,—C(O)—NH—, —SO₂NH— or —SO₂—, R¹ is a hydrogen atom or a group —NR²R³,wherein R² and R³ are each independently of the other a C₁₋₆alkylradical, and m is an integer from 12 to
 18. 7. A process for thepreparation of a surface-treated pigment according to claim 1,comprising the reaction of a diazonium salt of formula

wherein n, X¹, X², Ar¹ and Ar² are as defined in claim 1, with anorganic pigment or a mixture of organic pigments, including a solidsolution or a crystalline solid solution, optionally in the presence ofa reducing agent.
 8. Use of a surface-treated pigment according to anyone of claims 1 to 6 in the colouring of a high molecular weight organicmaterial.
 9. Use according to claim 9, wherein the surface-treatedpigment according to claim 6 is used in the mass-colouring of partiallycrystalline plastics.
 10. A coloured high molecular weight organicmaterial, containing (a) from 0.05 to 70% by weight, based on the sum of(a) and (b), of the surface-treated pigment according to any one ofclaims 1 to 6, and (b) from 99.95 to 30% by weight, based on the sum of(a) and (b), of a high molecular weight organic material.